Isolation of a cDNA encoding a protease from Perinereis aibuhitensis Grube

A critical review on marine serine protease and its inhibitors: A new wave of drugs?

Marine organisms are rich sources of enzymes and their inhibitors having enormous therapeutic potential. Among different proteolytic enzymes, serine proteases, which can be obtained from various marine organisms show a potential to biomedical application as thrombolytic agents. Although this type of proteases plays a crucial role in almost all biological processes, their uncontrolled activity often leads to several diseases. Accordingly, the actions of these types of proteases are regulated by serine protease inhibitors (SPIs). Marine SPIs control complement activation and various other physiological functions, such as inflammation, immune function, fibrinolysis, blood clotting, and cancer metastasis. This review highlights the potential use of serine proteases and their inhibitors as the new wave of promising drugs.

A novel alkaline serine protease with fibrinolytic activity from the polychaete, Neanthes japonica

A new protease named NJP with fibrinolytic activity was isolated from Neanthes japonica (Izuka), by a combination of ammonium sulfate fractionation, hydrophobic chromatography, ion-exchange chromatography and gel filtration. The molecular mass of NJP was approximately 28.6-33.5kDa as estimated by MALDI-TOF mass spectrometry and SDS-PAGE, which revealed a monomeric form of the protease. The isoelectric point of NJP determined by 2-DE was 9.2. NJP was stable in the range of pH 7.0-11.0 with a maximum enzymatic activity at 40°C and pH 9.0. The hydrolyzing activity of NJP on fibrinogen started from the Aα-chain, followed by the Bβ-chain, and the γ-chain at last. NJP had also a higher specificity for the chromogenic substrate S-2238 for thrombin. NJP activity was completely inhibited by PMSF. Analysis of partial amino acid sequences showed that NJP had very low homology with other known fibrinolytic enzymes. These results indicate that NJP is a novel alkaline thrombin-like serine protease. Thus NJP may have potential applications in the prevention and treatment of thrombosis.

Neanthes japonica (Iznka) fibrinolytic enzyme reduced cerebral infarction, cerebral edema and increased antioxidation in rat models of focal cerebral ischemia

Thrombolytic agent is increasingly being used in treating acute ischemic stroke. A novel protease with strong thrombolytic activity, Neanthes japonica (Iznka) fibrinolytic enzyme (NJF) discovered in our laboratory has been reported with characteristics of direct hydrolyzing fibrin and fibrinogen. The neuroprotective effect of NJF and urokinase (UK) was tested in rat models of middle cerebral artery occlusion (MCAO). The model was successfully produced by introducing an intraluminal suture into the left middle cerebral artery (MCA). NJF (0.25, 0.5, 1mg/kg) was injected intravenously 1h after the onset of reperfusion. Compared with vehicle group, MCAO animals treated with NJF showed dose dependent reduction in cerebral infarction with improved neurological outcome. Meanwhile, ischemia induced cerebral edema was reduced in a dose dependent manner. Treatment with NJF at 0.5mg/kg was almost equivalent to UK at 15,000U/kg dosage in the reduction of cerebral infarction and cerebral edema. Biomedical assay showed that NJF treatment suppressed lipid peroxidation and restored superoxide dismutase (SOD) activities in brain tissue. These results suggest that NJF posses neuroprotective potential in rat MCAO and reperfusion model. Neuroprotection shown by NJF may be attributed to inhibition of lipid peroxidation, increase in endogenous antioxidant defense enzymes.

Purification and characterization of a novel fibrinolytic enzyme from the polychaete, Neanthes japonica (Iznka)

A novel fibrinolytic enzyme from Neanthes japonica (Iznka), named NJF, was purified to electrophoretic homogeneity using ammonium sulfate precipitation, hydrophobic interaction, ion exchange and gel-filtration chromatography. NJF consisted of a single polypeptide chain with a molecular weight of 28-32 kDa, which was determined by MALDI-TOF mass spectrum and SDS-PAGE. The isoelectric point of NJF determined by isoelectric focusing electrophoresis (IEF) was 4.4, and the maximum activity of the enzyme was observed at 60 degrees C and pH 9.0. The cleavage speed of fibrinogen by NJF affected the Aalpha-chain first, followed by the Bbeta-chain and finally the gamma-chain. NJF activity was strongly inhibited by PMSF, indicating that it is a serine protease. Partial amino-acid sequences of its fragments were different from those of other known fibrinolytic enzymes. N. japonica may thus represent a potential source of new therapeutic agents to treat thrombosis.

Purification and properties of the protease from Perinereis aibuhitensis Grube

AIM: To purify a new protease from the clamworm Perinereis aibuhitensis Grube, and study its properties.

METHODS: After homogenization, Superdex-75 chromatography, MonoQ^TM chromatography, and SP-Sepharose 4B chromatography were used ordinally to purify the protease from the clamworm Perinereis aibuhitensis Grube. A new gelatin zymography method was used to study the proteolytic activity of the protease: protease separated by non-reductive SDS-PAGE was electrophoretically transferred to a gel containing gelatin, and the proteolytic activity of the protease was determined by the clear zone of the electrophoretic protein band. The effect of pH value, temperature, protease inhibitor, organic solvents and metal ions on the proteolytic activity of the protease was studied.

RESULTS: After purification, one kind of protease was obtained, which showed two protein bands with molecular weights of 34900 and 33900 separately by reductive SDS-PAGE, while three bands with molecular weights of 65600, 57900, and 43500 separately by non-reductive SDS-PAGE. Gelatin zymography showed that the proteolytic activity mainly appeared around the band of M_r 66000. The protease was stable and displayed high proteolytic activity within the range of pH 8 to 10 and at 20-35 ℃ It was strongly inhibited by phenylmethyl sulfonyl fluoride (PMSF), while stable in the presence of organic solvents.

CONCLUSION: The protease is composed of two subunits, whose molecular weights are 33900 and 34900, respectively. Gelatin zymography is sensitive and effective in studying the proteolytic activity of proteases.